Arduino UNO + CAP1188 with external power supply

Hi,

I connect Aeruino UNO and CAP1188 with I2C (scl, sda, reset pin) an everything works great. If I unplug Uno from computer an connect it with external power supply CAPP1188 does not work. I can not figure out why.

Please help!!

Maybe because you forgot to connect the grounds?

I tried both.

  • Uno and CAP are connected to the power supply.
  • Uno connected to power supply and CAP to Uno 5V and GND.

In both cases, GND is connected between Uno and CAP.

Post a complete wiring diagram of your setup!

  • Uno connected to power supply and CAP to Uno 5V and GND.

According to the datasheet the chip must not be driven with more than 4V.
Are you using the chip directly or is it on a breakout board? If later is true, post schematics of this board!

CAP1188:

Wiring:

CAP1188 UNO

sda ----------> sda
sck ----------> scl
rst -----------> D2
VIN ----------> 5V
GND ----------> GND

instructions:

Please specify what "does no work" actually means: Does it simply not detect the touches but the chip is responive and reacts otherwise correctly? Is the chip not visible on the I2C bus? Is the functionality there but not reliable?